concise and efficient synthetic route for preparation of four gangliosideGM3 analogues was described. The key step is a highly regioselective and stereoselective α-sialylation from a suitably protected glycoside acceptor with a sialyl xanthate to provide the sialo-oligosaccharide in good yield. The cytotoxic properties of the synthetic gangliosides were evaluated against normal human keratinocytes and human